Hey everyone, I just released a bolt catch that works with .22 conversion uppers. I figured this would be the place to get some good feedback. The first three people to post in this thread will get a free piece. FAQ - What is this bolt catch compatible with? It is compatible with: Spike’s Tactical dedicated upper receivers Spike’s Tactical conversion bolts Ceiner kit conversion bolts Tactical Solutions upper receivers - slight modification might be needed Other similar Atchisson style bolts We are working on a version 2 that will be compatible with Colt conversion bolts and M261 conversion bolts. Does this bolt catch feature a last round bolt hold open? The bolt catch does not by itself, but Black Dog Magazine's V3 magazine has a modified follower that will give true last round hold open. With the combination of the new magazines and the bolt catch, the rifle will function like a standard AR-15. This will not work with full auto rifles Do you ship internationally? Yes, we will ship anywhere you would like. International shipping is $4 a piece. This bolt catch is only compatible with .22 conversions. In the future we will be coming out with a dual caliber version but it's still a ways out. http://www.ARCatch22.com